• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.1 s.173
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• pp.38-51
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• 2000

The study on the mechanical behavior of a spot-welded specimen is largely divided into the quasi-static overload failure analysis and the fatigue failure prediction. The main issue in an overload analysis is to examine the critical loads, thereby providing a generalized overload failure criterion. As the welding spot forms a singular geometry of an external crack type, fatigue failure of spot-welded specimens can be evaluated by means of a fracture parameter. In this study, we first present the limit loads of 4 representative types of single spot-welded specimens in terms of the base metal yield strength and specimen geometries. Recasting the load vs. fatigue life relationships experimentally, obtained here, we then predict the fatigue life of spot-weld specimens with a single parameter denoted the equivalent stress intensity factor. This crack driving parameter is demonstrated to successfully describe the effects of specimen geometry and loading type in a comprehensive manner. The suggested fatigue life formula for a single spot weld can play a key, role in the design and assessment of spot-welded panel structures, in that the fatigue strength of multi-spots is eventually determined by the fatigue strength of each single spot.

• The Journal of Korean Society for School & Community Health Education
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• v.19 no.2
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• pp.31-42
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• 2018

Objectives: This study was conducted to analyze the mediating effect of self-identity on the relationship between aggression and school life adaptation of early adolescents. Methods: This study used the 5th-year data of the Korean Children & Youth Panel Survey (KCYPS) including 159 middle school 2nd students from single-parent families. The data was analyzed with open source statistics program R 3.5.0 to determine whether self-identity had a mediating effect on school life adaptation as an independent variable. Results: A moderate correlation was found among aggression, self-identity, and school life adaptation. As a result of the Sobel test, self-identity of early adolescents demonstrated a significant mediating effect on the relationship between aggression and school life adaptation. Conclusions: Given the significant mediating factor of self-identity, the strategies for early adolescents to boost their overall school life adaptation should be considered through intervention programs that help to enhance their self-identity.

• Journal of Ecology and Environment
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• v.31 no.3
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• pp.207-211
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• 2008

We investigated the leaf demography of a temperate woody liana, Akebia trifoliata, in a temperate forest in Japan, Akebia is semi-evergreen: some leaves are shed before winter, while others remain through the winter. Previous studies of semi-evergreen species found that variation in leaf life span was caused by variation in the timing of leaf emergence, Leaves that appeared just before winter over-wintered, while leaves appearing earlier were shed, However, it is unclear whether leaves of the same cohort (i.e., leaves that appear at the same time within a single site) show variation in life span under the effect of strong seasonality. To separate variation in life span among the leaves in each cohort from variation among cohorts, we propose a new method - the single leaf diagram, which shows the emergence and death of each leaf. Using single leaf diagrams, our study revealed that Akebia leaves within a cohort showed substantial variation in life span, with some over-wintering and some not. In addition, leaves on small ramets in the understory showed great variation in life span, while leaves on large ramets, which typically reach higher positions in the forest canopy, have shorter lives, As a result, small ramets were semi-evergreen, whereas large ramets were deciduous, The longer lives of leaves on small ramets can be interpreted as a shade-adaptive strategy in understory plants.

• Journal of the Korea Convergence Society
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• v.12 no.8
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• pp.67-75
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• 2021

This study was conducted to verify the factors affecting self-esteem of the 50-69 aged with low income in single person households. The subjects were 233 single households in the 50-69 aged low income from the 2019 welfare panel data provided by the Ministry of Health and Welfare. The dependent variable was defined as self-esteem, and independent variables were relationship satisfaction and life satisfaction. Data analysis was carried out by using SEM analysis, As a result, relationship satisfaction did not have a direct effect on self-esteem, with a low value (path coefficient =0.24). However, relationship satisfaction positively influenced life satisfaction (path coefficient =0.71), and life satisfaction positively influenced the self-esteem (path coefficient =0.46). Thus life satisfaction between relationship satisfaction and self-esteem had a mediator effect on self-esteem with 0.32 value. Therefore, establishing the strategy which supports poor single person households, policy makers should consider methods improving relationship satisfaction and life satisfaction.

• Journal of Family Resource Management and Policy Review
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• v.28 no.1
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• pp.13-25
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• 2024

The rate of single-person households has been increasing all over the world, and there has been a particularly rapid increase in them in Korea. Single-person households show unique and various characteristics related to the reasons for becoming a single-person household, gender, life cycle, and so on. Thus, research needs to focus on the specific groups of single-person households in order to provide tailored policies and programs. This study segmented single-person households in three groups based on life cycle: young, middle-aged, and older adults. Differences in the level of healthy lifestyle, as well as factors affecting that, were investigated according to the groups. The data were collected in 2022, with 237 respondents from single-person households in Kimpo. Descriptive statistics, t-test, ANOVA, and multiple regression analysis were conducted. The overall level of healthy lifestyle was found to be significantly higher for young adults compared to older adults. Results from multiple regression show that significant factors related to the healthy lifestyle of single-person households were gender, educational attainment, whether becoming a single-person household was voluntary, and whether the respondents had experienced discrimination as a single-person household. Significant factors differed by the sub-categories of the healthy lifestyle scale. This study has implications related to discovering differences in the level of healthy lifestyles of single-person households through examining the factors affecting it according to life cycle.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.3
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• pp.36-42
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• 2014

Domestic 105mm HE (High Explosive) shell is composed of three parts that are Fuze, Projectile and Propellants. Among three parts, propelling charge of propellants part consists of single base propellants. It has been known that the lifespan of single base propellants is affected by a storage period. These are because Nitrocellulose (NC) which is the main component of propelling gunpowder can be naturally decomposed to unstable substances similar with other nitric acid ester. Even though it cannot be prevented fundamentally from being disassembled, a decomposition product ($NO_2$, $NO_3$, and $HNO_3$) and tranquillizer DPA (Diphenylamine) having high reactivity are added into a propellant to restrain induction of automatic catalysis by a decomposition product. The decay rate of the tranquillizer is also affected by a production rate of the decomposition product of NC. Therefore, an accurate prediction of the Self-Life is required to ensure against risks such as explosion. Hereupon, this paper presents a new methodology to estimate the shelf-life of single base propellants using data of ASRP (Ammunition Stockpile Reliability Program) to domestic 105mm HE (propelling charge of propellants part). We selected four attributes that are inferred to have influence on distribution of the DPA amount in a propellant from the ASRP dataset through data mining processes. Then the selected attributes were used as independent variables in a regression analysis in order to estimate the shelf-life of single base propellants.

• Journal of Family Resource Management and Policy Review
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• v.18 no.2
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• pp.121-141
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• 2014

The purpose of this research is to determine how effective individual resources, family resources and developed environmental resources are in assisting the adaptation of a single parent's child to school life. The subjects were 284 first-year middle-school students with a single parent who were included in the first year of the Korean Children and Youth Research Panel 2010 data. The data were statistically processed using SPSS 18.0software. The results were as follows. First, the research participants' adaptation to school life, self-esteem, self-resilience, and peer relations were all shown to have an average of higher than 2 on a 4-point scale. Positive perceptions of parenting attitudes were 2.87, and negative perceptions 2.38. Computer usage was high, scoring 2.42, but mobile phone usage was average, at 2.02. Of the participants, 83.8% did not participate in a club or extracurricular activity. Second, self-esteem, self-resilience, peer relations, and positive parenting attitudes were correlated positively with adaptation to school life, but relying on a mobile phone was correlated negatively. Third, regarding the consequences of the relative effectiveness of the variables for adaptation to school life, as self-esteem, self-elasticity, and positive perceptions of parenting attitudes increased, Adaptation of a single parent's child to school life was more successful. Additionally, as annual family income and reliance on mobile phones increased, students' adaptation to school was less successful.

• Journal of the Korean housing association
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• v.8 no.3
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• pp.111-118
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• 1997

This study is intended to analyze the preference of one-room apartment according to the type of life style of single people between 20 and 30 years age. The major findings were as follows: 1) The single people prefer the one-roon apartment(90.2%). 2) The Life styles were classified into 5 types: tradition preservation. self-fulfillment, fashion-pursuit. economy priority. convenience-pursuit. 3) The preference of a one room apartment is strongly influenced by all types of life styles regardless of tradition preservation.

• Tribology and Lubricants
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• v.11 no.3
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• pp.40-47
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• 1995

The engine oil life was examined experimentally for small size single cylinder engines. This study was conducted in the laboratory. An Eddy Current type engine dynamometer was used with a motorcycle and a cultivator engine. Physical and chemical properties of used oil was analyzed to examine the oil life. Flushed oil was used for the reference instead of the new oil. It were found that deterioration of dynamic viscosity and anti-wear property of engine oil was due to dilution by fuel not depletion of ZDTP.

• Journal of Families and Better Life
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• v.33 no.6
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• pp.115-128
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• 2015

This study aims to examine the general tendency of suicidal ideation in single person households and to analyse the differences and effects of related variables(sociodemographic variables, characteristics of single person households, happiness and depression) on suicidal ideation. For achieving these purposes, a survey was conducted using questionnaires, based on quota sampling that considers the distribution of population in each dong of one Gu in Gwangju. Finally, data of 686 single person households were used for analysis. The study findings were as follows. The average score of suicidal ideation in single person households was 6.47 points, it was somewhat higher as compared to prior research that was targeting general households. And the average score of happiness index was 4.17 points, depression was 33.11 points. The level of suicidal ideation in single person households was significantly different according to age, occupation, economic status, health status, period of single life, life satisfaction, and contact with family. In addition, the level of depression(${\beta}=.24$, p<.01) had the biggest effect on suicidal ideation in single person households and it was followed by happiness index(${\beta}=-.19$, p<.05) and family visit(${\beta}=-.15$, p<.05). The total explanatory power was 37%. These findings imply that it is important to find a high mental health risk group and treat it early, because there is a high possibility that single person households might have mental health problems by being isolated or alienated from society. In addition, diverse program and services designed to maintain familial bonds despite family members living separately are needed.